Using waveform element to build arrays

Question

Hello, there,
from this forum, I learned that i can use "get waveform components" to extra time and data from waveforms.  great.  but how do i build an array and output it to a file?  does it come as a strand of arrays as it is?  or do i need to loop it so the index will shift?
if you can help and have an example...you'd be awesome!
best,
ck

Answer 1

If you want to create an array of timestamps, one way to do it is like in the picture attached. Using Export Waveforms To Spreadsheet File will do this for you too, if I remember correctly. I don't use the function that much.
You data is not appended randomly but whether it is correct or not, I can't say without having the actual VI to run and knowing exactly what you are trying to do.
The function Write Characters to File is probably slowing things down. If you were to look inside the function, you would thatt every time it is called, the file is opened, written to, then closed. The file opening and closing takes some time as does the actual file writing. You can put the file open and close outside the loop so that each is only done once. The time it takes to do the file writing is determined by the amount of data and the type of data. You are converting to text and that requires more bytes to store each data point. You could, save the data as binary. This will result in a smaller file and a faster write. You other option is to defer the file write until after the while loop terminates. You could wire the signal data type to the edge of the while loop and enable auto-indexing. Then, the array of signals or waveform datatypes could be written all at once.
Message Edited by Dennis Knutson on 04-17-2006 07:40 AM
Message Edited by Dennis Knutson on 04-17-2006 07:40 AM
Attachments:
Build Time Array.JPG ‏8 KB